1. Field of the Invention
Aspects of the present invention relate to an apparatus and method for a universal plug and play (UPnP) service in a public network environment, and more particularly, to an apparatus and method to construct a private network and remove unnecessary UPnP traffic in order to support the UPnP service in the public network environment such as an apartment complex.
2. Description of the Related Art
Recently, with the widespread use of the Internet and developments made in digital technologies, related industries are engaged in improving home networking technologies to connect PCs, network equipment, audio/video (AV) equipment, electronic home devices, home automation equipment, etc., at home.
Universal plug and play (UPnP) is one of the leading industrial standards in the home network field, and provides diverse UPnP services (such as searching all devices that perform UPnP functions using a UPnP device discovery function, and performing device control, media playback, and media transmission through a UPnP control point).
In the UPnP device detection process, IP multicast packets are transmitted to detect UPnP devices, and the corresponding UPnP devices respond to the packet transmission through a unicast, which is a communication system for performing communications between a single transmitter and a single receiver on a network.
FIG. 1 is a view illustrating the structure of a public network. Generally, in the network structure as illustrated in FIG. 1, public IPs and private IPs coexist in a large-scale network environment such as an apartment complex or an industrial complex. In the following description, an apartment complex structure will be exemplified.
A complex router 101 is a router or a gateway that serves to provide connections among public IPs and private IPs. In the case of transmitting data from private IPs allocated in the complex to an outside, the complex router 101 performs mapping of the data onto the public IPs having been restrictively allocated. In the case of transmitting data received through the public IPs to the private IPs, the complex router performs the mapping of the data onto the corresponding private IPs. The complex router 101 also prepares, manages, and converts a mapping table.
An apartment-unit or floor-unit connection device 102 is a device that distributes private IPs in the complex to respective households and floors of apartment buildings, and performs a switching or routing of the corresponding IPs. The connection device 102 is constructed to perform a hub function, or to perform either a switching function or a routing function, in accordance with the number of households in the complex.
A household connection device 103 performs connections with IP devices of a respective household, transmits data generated from the household to an outside, and transfers the data flowing into the household to the IP devices of the household. Generally, the household connection device 103 includes a multiplexer that operates as a repeater, a hub, and a router.
A UPnP household network 104 may be a service network that includes UPnP devices 103a for shared services using a UPnP function and can perform an automatic sharing of services and devices in an environment where an IP network is shared. The UPnP devices 103a include all IP devices and a control point having UPnP modules defined in the UPnP device architecture, and a UPnP media server, a renderer, and an AV control point defined in the UPnP AV architecture.
In FIG. 1, the defined network defines the respective households in the unit of an IP C class or a sub-class. Thus all UPnP multicast packets may be transmitted to other households through a hub, switch, router, and so forth.
However, there is a problem due to the fact that the UPnP multicast packet has a TTL (Time To Live) value of 4, and is transmitted using a multicast address. The setting of the TTL value to 4 indicates that the transmission can be performed through four routers. Accordingly, in the defined network as shown in FIG. 1, the transmitted UPnP multicast packet can reach the UPnP devices 103a of all of the households. Also, by using multicast addresses, all devices that can recognize and analyze the corresponding multicast IP can respond to the UPnP multicast packet.
Accordingly, the devices of all of the households having the UPnP modules can receive the UPnP device discovery multicast packet, respond, and transmit request packets. However, this causes a problem that the sharing of the UPnP content and the control devices is not performed in the unit of a household, but is performed in the whole unit (i.e., all of the households).
As a result, privacy (including personal privacy and a household member's content) cannot be secured, and the security of the control device cannot be guaranteed, so that the devices are exposed to serious attack.
Accordingly, in applying the UPnP to the network, a need exists for schemes to divide the household networks in order to guarantee the private protection and security in the unit of a household.
In addition, since a multicast packet is always transmitted to all ports, and devices having received the corresponding multicast packet respond using a unicast packet, this may result in whole network traffic overhead. As a result, the multicast packet is copied and transmitted to all ports, and this may cause the processing performance of the apartment-unit or floor-unit connection device 102 to deteriorate.
In order to guarantee the security of the UPnP device and prevent the performance deterioration of the UPnP device, U.S. Patent Unexamined Publication No. 2005-0240758 discloses a “controlling device on an internal network from an external network”. However, the above-described problems have not yet been solved.